River transport of carbon to the ocean is not on a scale that will bail humans out of our CO2 problem. Up to now it was not actually known how much carbon the world's rivers routinely flush into the ocean - an important piece of the global carbon cycle. But in a new study scientists have calculated the first direct estimate of how much and in what form organic carbon is exported to the ocean by rivers. The estimate will help modelers predict how the carbon export from global rivers may shift as Earth's climate changes. [Source: Woods Hole Oceanographic Institute]